Method of producing a spirally wound tube



p 1969 c. K. DUNLAP, JR., ET AL 3,468,733

METHOD OF PRODUCING A SPIRALLY WOUND TUBE Filed Jan. 5, 1966 C A LE5 K. bUNLAP, I2. 8 1131 S'AMes A. Fmm

ATTORNEY INVENTORSI United States Patent 3,468,733 METHOD OF PRODUCING A SPIRALLY WOUND TUBE Charles K. Dunlap, Jr., and James A. Fink, Hartsville,

S.C., assignors to Sonoco Products Company, Hartsville, S.C., a corporation of South Carolina Filed Jan. 5, 1966, Ser. No. 519,819

Int. Cl. B31c 3/04 US. Cl. 156-190 2 Claims ABSTRACT OF THE DISCLOSURE A method of winding a spirally wound tube .on a winding mandrel provided with a recessed helical groove wherein a relatively narrow strip of paper is spirally wound in the mandrel groove together with a relatively wide paper strip spirally wound in overlying relationship therewith on the mandrel winding surface with adhesive therebetween and with the spiral seam of the relatively wide strip positioned approximately intermediate the side edges of the narrow strip.

This invention relates to spiral tubes and more particularly to a spirally wound paper tube and a method of winding such a tube.

Spiral tubes and in particular spirally wound paper tubes are in widespread use today for a multitude of purposes such as the winding of sheet material including paper, plastic film and the like. Such spiral tubes are required to possess certain minimum strength characteristics such as beam and crush strength so as to receive the windings of sheet material without collapsing. In order to provide the desired degree of strength in such spirally wound paper tubes they are commonly formed from a plurality of plies of spirally wound paper strips arranged in staggered relationship with adhesive therebetween to hold the plies together in the spiral tube form.

As can be understood, such a spiral tube generally requires at least two plies for mutual retaining engagement so as to hold the plies together in the spiral tube form. This required use of at least two plies adds materially to the cost of such a tube from both the standpoint of the paper equired for the additional plies as well as the additional adhesive required to secure the overlying plies together. Such additional cost factors represent the difference between commercial success and failure in many instances where it is required that an absolute minimum of cost be represented by the spiral tube or core on which the relatively costly sheet material is wrapped.

Accordingly, a primary object of this invention is to provide a new and novel spiral tube.

Another object of this invention is to provide a new and novel method of winding a spiral tube.

A further object of this invention is to provide a new and novel spiral tube utilizing only a single body ply.

Still another object of this invention is to provide a new and novel spiral tube of one body ply construction which requires only a minimum amount of paper and adhesive so as to be relatively inexpensive to manufacture but at the same time is snfficiently strong and durable so as to be capable of being wound with a wide variety of sheet materials.

This invention further contemplates the provision of a new and novel method of winding a spiral tube on a mandrel which permits the tube to be wound in a simple and easy manner using many of the conventional spiral tube winding principles, which insures alignment of the strips from which the tube is wound and which promotes adhesion between the wound strips.

Other objects and advantages of the invention will become apparent from the following description taken in connection with the accompanying drawing.

The objects stated above and other related objects in this invention are accomplished by winding a relatively wide body ply of strip material such as paper into a tubular body having a spiral seam utilizing a spiral tube winding operation. At the same time, a relatively narrow strip of material, preferably also paper, having adhesive applied thereto is spirally wound over the spiral seam on the tubular body. This relatively narrow paper strip is thus adhesively secured to the edge portions of the body ply adjacent the spiral seam and maintains the body ply spirally wound into the tubular body to form a spirally wound paper tube.

The novel features which are believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation may be best understood by reference to the following description taken in conjunction with the accompanying drawing in which:

FIGURE 1 is a side view of the spiral tube of the invention;

FIGURE 2 is a schematic plan view of winding apparatus for forming the spiral tube of FIGURE 1 and for carrying out the method of the invention;

FIGURE 3 is an enlarged plan view of a portion of the mandrel of the winding apparatus of FIGURE 2;

FIGURE 4 is a sectional view taken substantially along line 4-4 of FIGURE 1 in the direction of the arrows;

FIGURE 5 is a view similar to FIGURE 2 showing a modification of the invention; and

FIGURE 6 is a side view of a portion of the spiral tube formed with the arrangement of FIGURE 5.

Referring now to the drawing and to FIGURE 1 in particular, there is shown a spiral tube formed in accordance with the invention and designated generally by the reference character T. Although the spiral tube T may be formed of any suitable material, it is preferably formed of a fibrous material such as paper.

The spiral tube T includes a relatively wide body ply 12 which is spirally wound as shown in FIGURE 1 into a tubular body having an inner surface 13 and an outer surface 14. The single body ply 12 is spirally wound with the edges of adjacent convolutions in abutting relationship to form a spiral seam 16.

A relatively narrow strip 17 of material such as paper is also spirally wound over the spiral seam 16 of the tubular body formed by the body ply 12. By means of an adhesive which is preferably applied to one surface of the relatively narrow strip 17, the strip 17 is secured to edge portions of the body ply 12 adjacent the spiral tube seam 16 with the seam 16 preferably substantially intermediate the side edges of the strip 17 as shown.

In the embodiment of FIGURE 1, the strip 17 is secured to the inner surface 13 of the spirally wound ply 12 and maintains the body ply 12 spirally wound into the tubular body to form the spiral tube T of the invention. Thus, the spiral tube T employs only a single body ply 12 together with a relatively narrow strip 17 which prevents the single body ply 12 from unwinding from the spirally Wound tubular body forming the spiral tube T.

The spiral tube T of FIGURE 1 is formed utilizing a novel method as illustrated schematically by the spiral tube winding apparatus of FIGURE 2. The spiral tube winding apparatus of FIGURE 2 includes a mandrel 18 supported at one end in a suitable frame 19 and a flexible endless belt 21 extending around a pair of pulleys 22, 23 at least one of which is driven for rotating and advancing the tube T in the direction of the arrow I as it is formed in the well known manner.

The mandrel 18 includes a guide portion 18a adjacent the fixed end of the mandrel and a smooth cylindrical portion 18b forwardly of the section 18a having an outer diameter corresponding generally to the inner diameter of the spiral tube T defined by the strip 17. The mandrel guide portion 18a is formed with a spiral groove 23 extending substantially throughout its length which accommodates the relatively narrow paper strip 17 during the winding operation. Thus in one embodiment of the invention, the spiral mandrel groove 23 is approximately 1 inch in width to accommodate a strip 17 having a width of 1 inch and is approximately 0.009 inch in depth to accommodate said strip 17 of approximately 0.015 inch in thickness. The groove 23 is preferably of such a depth so as to permit the strip 17 seated therein to project above the outer surface of the mandrel portion 18a thus insuring contact with the overlying body ply 12.

In the winding of the spiral tube T by the novel method of the invention, the paper strip forming the relatively wide body ply 12 is unwound in the direction of the arrow P from a supply roll (not shown) and wound onto the mandrel 18 with the edges of adjacent convolutions in abutting relationship to form the spiral seam 16. At the same time, the relatively narrow strip 17 is similarly unwound in the direction of the arrow Q from a supply roll (not shown). The strip 17 is conducted through a glue applicator designated generally by the numeral 24 and spirally Wound onto the mandrel 18 between the mandrel and the strip 12 within the mandrel groove 23.

In order to adhere the strip 17 to the body ply 12, the strip 17, advancing through the glue applicator 24 is maintained in contact With an applicator roll 26 suitably supported for rotation in the glue applicator 24. Contact between the applicator roll 26 and the strip 17 is maintained by suitable guide rolls 27 supported for rotation on the glue applicator as shown in FIGURE 2 so that the applicator roll 26 applies adhesive to the surface of the strip 17 which subsequently contacts the ply 12 when the strips 12, 17 are wound onto the mandrel 18.

During the winding operation of FIGURE 2, the strip 12 is positioned so as to locate the spiral seam 16 approximately intermediate the side edges of the relatively narrow strip 17 so that the strip is adhesively secured to the edge portions of the body ply 12 adjacent the spiral seam 16 as shown best in FIGURE 1 to maintain the body ply 12 spirally wound into the tubular body to form the spirally wound tube T.

As the tube T formed by the strips 12, 17 wound together moves in the direction of the arrow I by means of the belt 21, the strip 17 moves along the groove 23 throughout the mandrel portion 18a until it emerges at the groove opening 23a securely and permanently glued to the overlying body ply 12. Subsequently, further movement of the formed spiral tube T takes place along the smooth mandrel portion 18b with the continuously formed spiral tube T cut into appropriate lengths in the well known manner by suitable cutoff means (not shown).

It should be understood that the paper strip 12 may be of any suitable width within a wide range for forming the spiral tube T such as is commonly found in spiral tubes manufactured today. The width of the strip 17 need only be such as to provide for positive adhesion between the strip 17 and the edge portions of the ply 12 adjacent the seam 16 for maintaining the tube T in the wound condition. In one embodiment of the invention, the width of the strip 17 is /3 the width of the strip 12 so that a 1 inch strip 17 is used together with a 3 inch width strip 12 to form the tube T.

FIGURES 5, 6 show a modification of the invention in which a modified method of winding is employed to produce a modified spiral tube T. The spiral tube T of the modification utilizes a relatively wide body ply 31 having an inner surface 32 and an outer surface 33. The body ply 31 is Wound similarly to the body ply 12 of the embodiment of FIGURE 1 with the edges of adjacent con- 4 a J N 1 volutions in abutting relationship to provide a spiral seam 34. However, the relatively narrow strip of the embodiment of FIGURES 5, 6 identified by the numeral 36 is spirally wound onto the outer surface 33 of the body ply 31 and is adhesively secured to edge portions of the body ply outer surface 33 adjacent the spiral seam 34. The strip 36 functions similarly to the strip 17 of the embodiment of FIGURE 1 in that only a single body ply 31 is employed which is held spirally wound in the form of a tubular body by the strip 36 to form the spiral tube T.

In carrying out the modified method of the invention with the apparatus of FIGURE 5 'by means of which the tube T is produced, a smooth surfaced mandrel 41is provided supported at one end in a frame 42 and has associated therewith a winding belt 43 extending around belt pulleys 44, 46. The strip 31 forming the relatively wide body ply of the tube T is advanced in the direction of the arrow M and spirally wound onto the mandrel 41 as shown. The strip 36 to which adhesive is applied in the glue applicator 47 is advanced in the direction of the arrow N and spirally wound on the outer surface of the.

wound strip 31 as shown over the spiral seam 34. The glue applicator 47 includes guide rolls 48 and an applicator roll 49 which applies glue to that surface of the strip 36 which contacts the underlying wound strip 31 and the strip 36 is positioned so that it is adhesively secured to the edge portions of the wound strip 31 adjacent the spiral seam 34 intermediate the side edges of the strip 36. As in the embodiment of FIGURES 14, the wound tube T is moved in the direction of the arrow R by means of the belt 43.

It can be seen that there has been provided with the novel construction of this invention a spirally wound tube which may be formed from relatively soft weak material such as paper and utilizing only a single body ply while achieving strength characteristics adequate to support windings of sheet material without collapsing. An outstanding feature of the invention is the elimination of a second body ply presently required to maintain spirally Wound paper tubes in the Wound condition utilizing present day spiral tube winding practices. Not only does the elimination of the second ply simplify the manufacture of the spiral tube of the invention but in addition a substantial saving in paper and adhesive costs result permitting the production of a far cheaper tube than presently manufactured for the same purposes. By the novel method for forming the spiral tube of the invention, the tube may be inexpensively and easily wound at a high production rate with an elimination of such problems as unstuck plies, and a reduction of start-up time for tube manufacture. In addition, the spiral tube of the invention may be formed selectively with the relatively narrow holding strip on the inside or outside of the single body ply without any sacrifice in utility or increase in cost thereby producing a remarkably simple commercially attractive throw-away paper tube of the type long required by purchasers While there has been described what at present is considered to be the preferred embodiment of the invention, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the invention and, therefore, it is the aim of the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the v invention. 7

Having thus described the-invention, what is claimed is: 1. A method of producing a spirally wound tube comprising the steps of, providing a winding mandrel having a winding surface, spirally winding a relatively wide strip of material on said mandrel windingsurface to form a tubular body having a spiral seam, simultaneously spirally winding a relatively narrow strip of material having adhesive on its outwardly facing side on said mandrel winding surface in underlying relationship with said relatively wide strip of material, positioning said wide strip of material during said winding steps to locate said tubular body spiral seam approximately intermediate the side edges of said narrow strip of material whereby said narrow strip is adhesively secured to the edge portions of said relatively wide strip of material adjacent said spiral seam.

2. A method of producing a spirally wound tube comprising the steps of, providing a winding mandrel having a winding surface and a helical groove in said winding surface, spirally winding a relatively wide strip of material on said mandrel winding surface to form a tubular body having a spiral seam, simultaneously spirally winding a relatively narrow strip of material having adhesive on its outwardly facing side on said mandrel winding surface in said mandrel helical groove in underlying relationship with said relatively wide strip of material, positioning said wide strip of material during said winding steps to locate said tubular body spiral seam approximately intermediate the side edges of said narrow strip of material whereby said narrow strip is adhesively secured to the edge portions of said relatively wide strip of material adjacent said spiral seam.

UNITED STATES PATENTS 9/1921 Ritchie 156-190 X 11/1932 Burton 156-190 X 6/1936 Tucker 156-190 X 9/1964 Couzens et a1 93-80 6/1967 Lee et al. 156-195 X 8/1967 Denen-berg 156-193 X 11/1967 Sato 93-80 X 4/1968 Carson et a1 156-425 X 5/1968 Roe 93-94 10/1967 Mills et al 138-130 X 9/ 1968 Mesrobian et al. 138-144 X 10/1968 Martin et al. 93-80 HAROLD ANSHER, Primary Examiner US. Cl. X.R. 

